Average Weather in Galveston Texas, United States
In Galveston, the temperature typically varies from 49°F to 90°F over the course of the year, and is rarely below 37°F or above 93°F.
The hot season lasts for 4.0 months, from May 27 to September 27, with an average daily high temperature above 84°F. The hottest day of the year is August 5, with an average high of 90°F and low of 80°F.
The cool season lasts for 3.0 months, from December 3 to March 2, with an average daily high temperature below 67°F. The coldest day of the year is January 6, with an average low of 49°F and high of 61°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
The length of the day in Galveston varies significantly over the course of the year. In 2017, the shortest day is December 21, with 10 hours, 16 minutes of daylight; the longest day is June 21, with 14 hours, 1 minute of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 6:19 AM on June 10, and the latest sunrise is 1 hour, 15 minutes later at 7:34 AM on November 4. The earliest sunset is at 5:20 PM on December 1, and the latest sunset is 3 hours, 2 minutes later at 8:22 PM on July 1.
Daylight saving time (DST) is observed in Galveston during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.
Sunrise & Sunset with Twilight and Daylight Saving Time
In Galveston, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year in Galveston begins around September 16 and lasts for 2.7 months, ending around December 8. On October 26, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 69% of the time, and overcast or mostly cloudy 31% of the time.
The cloudier part of the year begins around December 8 and lasts for 9.3 months, ending around September 16. On August 21, the cloudiest day of the year, the sky is overcast or mostly cloudy 53% of the time, and clear, mostly clear, or partly cloudy 47% of the time.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Galveston varies throughout the year.
The wetter season lasts 3.8 months, from May 26 to September 21, with a greater than 32% chance of a given day being a wet day. The chance of a wet day peaks at 42% on September 4.
The drier season lasts 8.2 months, from September 21 to May 26. The smallest chance of a wet day is 22% on April 1.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 42% on September 4.
Daily Chance of Precipitation
To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day in the year. Galveston experiences some seasonal variation in monthly rainfall.
Rain falls throughout the year in Galveston. The most rain falls during the 31 days centered around September 8, with an average total accumulation of 5.0 inches.
The least rain falls around March 4, with and average total accumulation of 3.1 inches.
Average Monthly Rainfall
We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.
Galveston experiences very significant seasonal variation in the perceived humidity.
The muggier period of the year lasts for 7.8 months, from March 27 to November 20, during which time the comfort level is muggy, oppressive, or miserable at least 28% of the time. The muggiest day of the year is July 20, with muggy conditions 100% of the time.
The least muggy day of the year is January 23, with muggy conditions 4% of the time.
Humidity Comfort Levels
This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.
The average hourly wind speed in Galveston experiences mildly seasonal variation over the course of the year.
The windier part of the year lasts for 8.4 months, from September 27 to June 9, with average wind speeds of more than 5.5 miles per hour. The windiest day of the year is December 25, with an average hourly wind speed of 6.6 miles per hour.
The calmer time of year lasts for 3.6 months, from June 9 to September 27. The calmest day of the year is August 15, with an average hourly wind speed of 4.5 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Galveston varies throughout the year.
The wind is most often from the south for 7.0 months, from February 5 to September 4 and for 3.6 weeks, from November 11 to December 6, with a peak percentage of 72% on June 27. The wind is most often from the east for 2.2 months, from September 4 to November 11, with a peak percentage of 45% on September 20. The wind is most often from the north for 2.0 months, from December 6 to February 5, with a peak percentage of 36% on January 1.
Galveston is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.
The average water temperature experiences significant seasonal variation over the course of the year.
The time of year with warmer water lasts for 4.1 months, from June 1 to October 3, with an average temperature above 80°F. The day of the year with the warmest water is August 14, with an average temperature of 86°F.
The time of year with cooler water lasts for 3.3 months, from December 11 to March 21, with an average temperature below 65°F. The day of the year with the coolest water is January 30, with an average temperature of 60°F.
Average Water Temperature
This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.
The average daily incident shortwave solar energy experiences significant seasonal variation over the course of the year.
The brighter period of the year lasts for 2.9 months, from April 4 to July 1, with an average daily incident shortwave energy per square meter above 5.9 kWh. The brightest day of the year is June 3, with an average of 6.6 kWh.
The darker period of the year lasts for 2.6 months, from November 14 to February 2, with an average daily incident shortwave energy per square meter below 3.7 kWh. The darkest day of the year is December 24, with an average of 3.0 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Galveston are 29.301 deg latitude, -94.798 deg longitude, and 3 ft elevation (map ).
The topography within 2 miles of Galveston is essentially flat, with a maximum elevation change of 20 feet, and an average elevation above sea level of 5 feet. Within 10 miles is also essentially flat (26 feet). Within 50 miles contains only modest variations in elevation (112 feet).
The area within 2 miles of Galveston is covered by artificial surfaces (54%), water (25%), and bare soil (11%), within 10 miles by water (80%), and within 50 miles by water (57%) and cropland (19%).
This report illustrates the typical weather in Galveston, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Galveston.
For each station, the records are corrected for the elevation difference between that station and Galveston according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Galveston is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Galveston and a given station.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for aiports and weather stations are provided by AskGeo.com .